Direct compression is the most commonly used method for the production of tablets. The process consists of various mixing steps. First, the active substance and all excipients (mainly filler, binding agent and disintegrating agent) except the lubricants are mixed together. This can be accomplished in a single mixing step, whereby the filler, binding agent and disintegrating agent are combined with the active substance. Alternatively, numerous sequential mixing steps may be carried out. Subsequently, the lubricant is added to the mixture and in turn mixed with said. The result is a tableting mixture. This is compressed in a tableting press.
In pharmaceutical technology, combined excipients are available (direct tableting excipients). These are combined tableting excipients which consist of numerous individual substances (frequently filler, binding agent and disintegrating agents) which are produced by means of co-processing (for example spray drying, compaction or granulation). These multi-functional substances demonstrate certain advantages over the physical mixture of the individual components. See EP 0 819 429.
All known combinations of filler, binding agent and disintegrating agents contain no lubricant. There are various reasons for this, particularly the danger of over mixing, lower tablet hardness and coatings of the tablets.